Orycteropus, GEOFFROY ST HILAIRE, 1796

Lehmann, Thomas, 2009, Phylogeny and systematics of the Orycteropodidae (Mammalia, Tubulidentata), Zoological Journal of the Linnean Society 155 (3), pp. 649-702 : 683

GENUS ORYCTEROPUS GEOFFROY ST HILAIRE, 1796

Diagnosis: Large-sized Orycteropodidae displaying the following apomorphic characters on the cranium: low temporal lines, and a post-palatine foramina positioned caudally to the M 3. On the post-cranium: six sacral vertebrae, the presence of a falciform process on the proximal epiphysis of the tibio-fibula, and a femur longer than the tibia. Moreover, this genus distinctively has a flat (or button-like) radial (or bicipital) tuberosity on the radius, possesses a deep dorsal notch between the tibial tuberosity and the fibula on the proximal epiphysis of the tibio-fibula, and shows a quadrate talus (subequal breadth and length). Additionally, all Orycteropus species are characterized by the combination of the following features: a rectilinear nuchal line; an anterior border of the orbit situated above the M 3; a ventralmost point of the maxillojugal suture caudal to M 3; a rectilinear postpalatine torus caudal to the M 3; a broad palate; the presence of a palatine groove; the absence of crests on the pterygoid; an interorbital constriction formed strictly by the frontal, orbitosphenoid, and the alisphenoid; the absence of canines; a rectangular outline of the upper and lower molars; a mandibular angle ranging from 60° to 73°; flat (or slightly convex on the mandible) craniomandibular articulation surfaces; a strong and projected laterally deltoid crest on the humerus; an oval and bounded proximally olecranon fossa on the humerus; a broad distal epiphysis of the humerus; a sharp oblique rim on the radius; a caput femoris oriented mediolaterally; an articular facet for the sesamoid bone of the gastrocnemius muscle on the femur positioned at the level of the diaphysis; a long tibial crest merging in a gentle slope close to the middle of the diaphysis of the tibia; and a concave and developed cotyloid facet on the talus.

Remarks: The original diagnosis of the genus given by Geoffroy St Hilaire (1796: 1) is very concise: ‘Orycterope. Orycteropus . Dents molaires (six), à couronne plate; corps recouvert de poils’. To the best of my knowledge, no other author has proposed another diagnosis for this genus.

Type species: Orycteropus afer ( Pallas, 1766) .

Other forms: Orycteropus crassidens MacInnes, 1956 ; Orycteropus djourabensis Lehmann et al., 2004 ; Orycteropus cf. afer Langebaanweg ( Hendey, 1973; Pickford, 2005; Lehmann, 2006b); Orycteropus cf. afer Makapansgat ( Kitching, 1963; Lehmann, 2004); Orycteropus cf. afer Swartkrans (Lehmann, 2004) ; Orycteropus aff. djourabensis Lothagam Lower Nawata ( Milledge, 2003); Orycteropus aff. djourabensis Lothagam Upper Nawata ( Milledge, 2003); Orycteropus aff. djourabensis Lukeino ( Pickford, 1975) ; Orycteropus sp. Asa Koma ( Lehmann, 2008a); Orycteropus sp. Laetoli ( Dietrich, 1942, Leakey, 1987); Orycteropus sp. Swartkrans (Lehmann, 2004).

Etymology: The genus name is a latinized form based on the Greek R (‘orukter’, a burier), which is a variation of (‘oryctes’), and PO (‘pous’, foot). It means litteraly: ‘digging foot’.

Geographic distribution: Africa.

Temporal distribution: Late Miocene to present day. The oldest record (O. sp.) is from the Lower Nawata Formation of Lothagam, dated to between 7.4 and 6.5 Mya ( Leakey & Harris, 2003).